Artificial leather



Patented Sept, 13, 1927.

UNITED STATES. PATENT OFFICE.

ROYAL -K. ABBOTT, OF CRANSTON, RHODE .ISLAND, A SSIGNOR RESPRO INC., OF

PROVIDENCE, RHODE ISLAND, A CORPORATION OF RHODE ISLAND.

7 ARTIFICIAL LEATHER.

No Drawing.

My invention herein describedrelates to the manufacture of sheet material resembling leather in visual appearance as. well as essential physical or structural properties, and employs forits basis sheet materials of the character invented by Roland B. Respess and described in his United States Letters Patent No. 1,524,573, dated January 27, 1925. It is characteristic of that sheet ma- 10 terial that at a preparatory stage of its manufacture it consists of a sheet of unwoven fibres, impregnated with a viscid, cementitious substance, but of loose or open texture, which, upon receiving a compressive treatment, becomes compactby the integration of previously separate or imperfectly integrated fibre-coatings of the cementitious material. The completed product described in said patent possesses the structural and I physical properties of leather in substantial degree, and is, indeed, stronger than many varieties or grades of leather of equal. body or thickness. Not onlyisthe stage-product above alluded to permeable by gases-though resistant to penetration by water" but' the final compacted product also is like leather permeable by gases, unless the original impregnation by cementitious material be so controlled as to carry into association with the fibres a proportion of the cementitious material so voluminous inits final coagulated, solidified, or dense condition that no interstices remain to permit permeation by gases. This material, when completed by the process described in the said patent, has 'a dull-appearing surface and thereforerequires the application of surface coatings or dressings if it is to simulate finished leather to the eye as well as in its structural and 40 physical properties. Surface coatings or dressings have been applied to such completed material by spreading or dressing machines in the well known manner, substan* tially as has been the practice in the manufacture of coated cloths,etc. for a long time,

and have served their intended purpose satisfactorily except when subjected to conditions which call for great tenacity of union between the material and its coating or dressing if the latter is to remain integrated with the former. The object of the mven- Application filed March so, 1926. Serial No. 98,623.

tion herein described is to produce a surface coated or dressed material of the character indicated in which the coating-film is so securely attached to the fibrous material as to be practically inseparable therefrom.

In the practice of my invention, I take advantage of'the structural peculiarities of the stage-product which appear in the manufacture of sheet material in accordance with the process described in the said Respess patent, and, instead of coating or surface-dressing the completed material, as heretofore, I first impregnate a loosely constructed sheet of unwoven fibres-such as cotton waddingwith viscid cementitious material such as rubber or a rubber composition in a solvent vehicle thereofintruding this into the sheet essentially in the mannerdescribed in the said patent; second, I allow the impregnated sheet, after the first step, to recover part of its original spacial dimension of thickness by virtue of the resiliency ofxthe fibres of which it is com posed, so that the impregnated sheet becoines reticularand easily permeable by a fluid (air, in the specific case) which so acts upon thecontent ofviscid cementitious mat'erial as to render it much more viscous and adhesively tenacious than it was when intruded into the assemblage of fibres, all substantially asset forth in the said patent.

At this stage, the impregnated sheet is relatively soft and loose in texture, though considerably reduced in thickness from its original condition; the constitutent fibres are each coated with adhesive cement which is in acondition of augmented tenacity and adhesiveness adapted to bring about and retain a much closer union of the constituent materials upon further compressive treatment. And, when the material has reached this intermediate stage, before the second or final compressive treatment, I apply to it and intrude into its pores or cavities from at least one of its surfaces by means of a knife, or other coating instrument, a priming or base coat of dressing, such as for instance a liquid, viscous or pasty extension or solution of or mixture containing a cellulose derivative, such as nitro cellulose, acetyl cellulose or other cellulose derivative or ester, of such consistency that it interpenetrates the fibrous sheet to the extent of en tering the pores of the material and enveloping the fibres (coated with the cementitious material originally introduced) at and near the surface of the material.

I recommend and prefer the employment of a coating or dressing composition of which the solvent is capable of wetting contact with the adhesive constituent of the cementitious material with which the fibres of the sheet material are already associated, so that the cementitious material adhering to the surface fibres may everywhere he in inti mate contact with the dressing material, so that the resultant shall serve as a factor producing ultimate union between the coating film or dressing and the cementing medium which binds the fibres together. The solvent for the coating material may in some cases be actually miscible with and serve as a softener for the cementit-ious binder of the base material, as, for example, when ethyl acetate is used with from ten to fifteen per centum by quantity of benzol. For example, if the original cementitious impregnant be a rubber composition with gasolene, naphtha, or the like as a solvent vehicle, and the coating or dressing composition be nitro cellulose extended or dissolved in amyl or ethyl acetate, with or without benzol, or a cellulose acetate extended or dissolved in acetone, the solvent constituent of the dressing remains in wetting contact with, and if benzol or like solvent is used, softens the rubber composition adhering to the surface fibres, in either case forming local association between the soluble constituent of the dressing and the rubber already present, and thus enhancing the intimacy of adhesive association between fibre, rubber and the surface layer and intruded interpenetrating extensions of the dressing material, which now ensues when the sheet material thus supplied with a surface-penetrating base coating or dressing, is subjected to a further compression, as in a calenderirg or embossing machine. I may, before finally compressing or calendering the material to its intended state of adhesive integration of fibre-cement inclusion and coating inclusion apply successive coatings of the surface dressing over the base-coat, allowing each coating to dry before applying the next; or I may defer the application of further surface coatings upon the base coating until after the material with the base coating attached has been consolidated by calendering. In either case, each of the successive coatings is preferably of such character as to unite (by solvent action) with the coatingtowhich it is applied. The coatings may be embossed as well as calendered, to produce whatever superficial appearance is desired. Calendering in some cases may follow embossing for special effects of grain.

ea-awe When the base coating is applied as above described to the material in its intermediate stage of production and while it is reticular in structure and superficially permeable by a varnish-like coating material, the base coat envelopes the surface fibres, or portions of them, as well as intrudes or penetrates into the grosser cavities of the relatively open unfinished base material, (like the relation of plaster to lathing) so that upon being dried or set to a tacky consistency, the said coating is anchored or tied to the fibres of the sheet material both by adhesion and by intruded keys of the coating. When, at a later stage of manufacture, the coated sheet is heavily compressed, this anchorage or tying of the coating to the fibres, and to the cementitious adhesive material originally ap' plied to the fibres, is rendered so tenacious and secure that the aggregate final finished coating or dressing (composed of several applications of dressing material) is so interlocked with the fibrous body and its cement that any attempt to pull the dressing from the sheet will result in rupture of the latter.

Specifically, I have found that coating solutions compounded as follows, yield satisfactory results in application to material having the characteristics above indicated:

For the base coating, nitrated cotton cut or dissolved in any of its well-known solvents, e. g. ethyl acetate, to form a 16 oz. solution, so-called (i. e. sixteen ounces of the solute to a gallon of the solvent). To this a pigment, ground in castor oil may be added to give a desired color. The addition of castor oil or other softeners may be resorted to in suilicient quantity to produce the desired degree of pliability. When the ingredients used have been thoroughly mixed, the solution is then thinned bv the addition of nitro cellulose solvent until the desired viscosity is obtained. I have found that a viscosity of about 28000 centipoises. as given by a Stormer viscosimeter, model 7650-A, and calculated by the Equations of Higgins 8:. Pitman (Journal of Industrial and Engineering Chemistry, vol. 12,-1920-page 587) is suitable to the purpose.

For superposed coatings, to the same 16 oz. nitrated cotton solution add 10% on the weight of the solution, of castor oil; to this add pigment ground in castor oil, and thin the whole with ethyl acetate until a viscosity about 28000 centipoises (determined as above stated) is reached.

For the purpose of this invention, the advantages secured are exemplified by the association, substantially as above described, of the open reticulated stage of rubber-cement integrated fibrous sheet base material with a surface coating material dissolved. softened or rendered plastic by an extender or solvent capable of intimate wetting contact lllll are ethyl acetate, amyl acetate, methanol,

acetone, phenol, camphor, formic acid, many organic esters of organic acids and inorganic acids; halogentated hydrocarbons of the aliphatic and aromatic series, and alkalinated carbon disulfide.

The coated sheet, made as above described, has been found entirely adequate in many respects to the manufacture of' shoes. as a substitute for leather. The flections and creasings to which the material described is subjected when used as parts of shoes, have no effect on the coating, which remains tenaciously attached to the tough fibrous sheet material. I

I claim;

1. Process of making artifical leather comprising a primary simultaneous compression of a sheet of resilient fibres and a viscid mass of cementitious substance, permitting the treated sheet to expand by the inherent resilience of its fibre component. subjecting the expanded sheet to treatment adapted to mcrea e the tenacity of the coating throughout the fabric spreading on this expanded fabrica fluid film-forming dressing of such con: sistency as to enclose cement-coated fibres at and near the surface of said sheet and form a continuous layer overlying the fibrous surface, allowing the film-forming dressing to set, and thereafter subjecting the surfacedressed sheet to compacting pressure.

2. Process of making artificial leather comprising as steps,- causing interpenetration of a flocculent sheet of fibres by a solidifiable viscid cementitious substance by a primary compression of the sheet and a mass of said substance, releasing pressure on the treated sheet to permit resilient recovery of coated fibres to a reticular. relatively open a state and exposing the expanded sheet and the substance carried thereby to treatment increasing the tenacity. and adhesiveness of said substance, spreading on the sheet While in its said reticular relatively open state a fluid film-forming dressing containing material adapted to wetting contact with the said cementitious substance and of such consistency as to enclose cement-coated fibres at and near the surface of said sheet and form a continuous layer overlying the fibrous surface, allowing the filmforming dressing to set, and thereafter compacting I the surface-dressed sheet.

3. Process of making artificial leather comprising a primary simultaneous compression of a sheet of resilient fibres and a.

adapted to increase the tenacity of the coat ing throughout the fabric, spreading thereon F i while in itssaid expanded condition a fluid the surface and to penetrate the grosser cavities of said sheet and form a continuous layer overlying the fibrous surface, allowing the film-forming dressing to set, and thereafter compacting the surface-dressed sheet by heavy compression.

4. Process of making artificial leather comprising a primary simultaneous compression of a sheet of resilient fibres and a viscid mass of cementitious, substance, permitting the treated sheet to expand by the inherent resilience of its fibre component, subjecting. the expanded sheet to treatment adapted to increase the tenacity of the coating throughout the fabric by depriving the cementitious substance of at least a part of its'liquid contents, then spreading thereon while in its said expanded condition a fluid film-forming coating containing material miscible with the said cementitious substance of such consistency as to flow into cavities of said sheet and form a continuous layer overlying the fibrous surface, allowing the film-forming dressing to set, and thereafter compacting the sheet and coating.

5. Sheet material useful as a substitute for leather, being the product of the process set forth in claim 1. to wit: having a base of vcement-integrated unspun, unwoven fibres,

the fibres being severally coated with cementitious material and the sheet bearing a coating film of colloidal material interpenetrating between the cement coated fibres at one face and in wetting contact therewith and forming a continuous layer overlying the fibrous surface, the whole being integrated as the result of pressure applied in the direction of the thickness of the sheet.

6. Sheet material useful as a substitute for leather, being the product of the process set forth in claim 1, and further characterized as follows :-having a base of rubber-cement-integrated unspun, unwoven fibres, the

fibres being severally coated with cementitioiis rubber and the sheet bearing a coating film of a hardened deposit from cementitious solution of a colloid substance capable of solution in a solvent miscible with rubber, said deposit interpenetrating between the rubber coated fibres at one face and in Wetting contact therewith and forming a continuous layer overlying the fibrous surface, the whole being integrated as the result of pressure applied in the direction of the thickness of the sheet.

7. Sheet material useful as a substitute for leather, being the product of the process set forth in claim 1. and further characterized as follows :having a base of cement-integrated unspun, unwoven fibres, the fibres be- ILL) 4 essee;

ing severally coated with cementitions'mate rial end the sheet bearing a set film of n. solution of a cellulose ester in a solvent capable of wettin contact with the eementitious ma,- terial, sai film interpenetrating between the cement-coated fibres at one face and in wetting contact therewith and forming a continuous layer overlying the fibrous surface, the whole being integrated as the result of pressure a plied in the direction of the thickness 0 the sheet.

Signed by me at Cranston, Rhode Island, this 27th day of March, 1926.

ROYAL K. ABBOTT. 

